Starting means for vapor electric apparatus



Oat.v 27, 1936. '1. w. MORTON 2,059,014

STARTING MEANS FOR VAPOR ELECTRIC APPARATUS Filed Nov. 8, 1932 2Sheets-Sheet 1 PHASE sun Fran I Invent-or: Lgsle W. Mo'rcon- ,HisAttorney.

- Oct. 27, 1936. w. MORTON 2,059,014

STARTING MEANS FOR VAPOR ELECTRIC APPARATUS FiledNov. 8, 1932 2Sheets-Sheet 2 FY 4, Inven tar":

' LldS|eW.MOYtOn,

UiRM 8.8

H s Attorneg.

Patented Oct. 27, 1936 "UNITED STATES PATENT, OFFICE STARTING MEANS FOR;VAPOR ELECTRIC APPARATUS Lysle w. Morton, Schenectady, N. Y., assignorto General Electric Company, a corporation of New York W inventionrelates to means for and methods of starting vapor electric apparatus,particularly of the mercury vapor type such as the mercury arcrectifier, and has for its principal object the provision of an improvedexcitation anode arrangement and method of operation whereby the pick-upoi the are by the main or power anodes is facilitated.

It is common practice in the operation of vapor electric devices of themercury arc type to accomplish the starting of the device by striking anare between the cathode and an ignition electrode to form a cathode spoton the mercury, then establishing a discharge current between thecathode and excitation anodes, and finally establishing the powercurrent between the cathode and the main anodes. One purpose ofestablishing the discharge current between the excitation anodes *andthe cathode is to provide ionization tor the main anodes to facilitatethe pick-up of the arc by the latter anodes.

v Certain types ofv such mercury are devices, particularly rectiiiers orthe like having in general excellent operational characteristics havebeen designed for large power and high voltage. To assist in preventingthe occurrence of arc-back in the above mentioned mercury are devicesintended for large power and high voltage operation it has been founddesirable to provide a high degree of baming, i. e., the provision oi!highly eiiicient baille elements such as anode shields, baflie membersproper in the arc path within the shields, grid members mounted adjacentthe anodes and functioning in part as bailies, and

35 other suitable bailie elements associated with the anodes or mountedin the arc path, or both. This provision of extremely eilicient baillinghas contributed largely to the high rating and voltage 0! the mercuryarc device by thus assisting in the 40 prevention of arc-back betweencathode and main anodes or elsewhere.

Diificulties have however been encountered in certain instances in theoperation of mercury are devices, particularly of the large power andhigh 5 voltage type above described-provided with a high degree ofbattling, due to hard starting or pick-up of the are by the main orpower anodes, this hard pick-up being attributable in part at least tothe presence of the bailiing which'as above noted con- 50 tributes tothe high power and voltage rating of the device.

I have found that the hard starting, or hard pick-up of the are by themain anodes encountered at times in certain types of vapor electric 55devices, for example of the high power mercury arc type above described,is due in great measure to the fact that, in spite of the provision ofex-.

- period immediately preceding and including the instant at which themain anodes should pick up the arc.

In accordance with my invention the above starting dimculties areovercome, and the ad- 15 vantages inherent in a high degree of baiiiingmay be retained, by the provision of excitation means preferablycomprising a plurality of excitation anodes so mounted with reference tothe main anodes and so energized from a suitable current source that atthe firing or pick-up periods of the main anodes or immediately beforethese firing periods, the ionization conditions in the main anoderegions and in the arc path are'such that easy pick-up oi! the are bythe main anodes is insured without danger of the occurrence of areback.

In carrying my invention into eflect I provide a plurality of excitationanodes each associated with a different one of the main or power anodes3o or-with a different group of the main anodes and each mounted in sucha predetermined position,

. with reference to the main anode group with which it is associated, inthe region of this associated main anode or group, that the ionizationprovided by each excitation anode to its corresponding main anode orgroup 01' main anodes comes into relatively close juxtaposition thereto.

The excitation anodes are energized preterably though not necessarilyfrom an alternating current source. In order to insure that theionization supplied by each excitation anode to its associated mainanode or group thereof, when v the excitation anodes are energized froman alternating current source, shall be supplied at such time that theionization will assist to the fullest extent the corresponding mainanode, or group in picking up-the are, means are provided to energizethe excitation anodes in the same sequence as that of the firing or arcpick-up periods of the corresponding main anodes or groups thereot. Tothis end potentials from a suitable source, as a transformer suppliedfrom the same alternating current source as that from which potentialsare impressed upon the. main anodes,

may be impressed upon the excitation anodes to cause the positivehalf-waves of the potential supplied to each of the excitation anodestooccur at substantially the same period as that of the positivehalf-wavesof the potential supplied to the corresponding main anode orgroup of main anodes, the firing or discharge periods of the excitationanodes thus substantially synchronizing with the firing or arc pick-upperiods of the main anodes or groups. V

I have found, however, that instead of substantially synchronizing thefiring periods of the excitation anodes and their corresponding mainanodes or groups, it may be necessary or desirable in certain instancesto operate the excitation anodes with potentials shifted to a certaindegree with respect to the phase of the potentials impressed upon thecorresponding anodes or groups. In accordance with my invention meansare, therefore, preferably provided to shift the phase of the excitationanode potentials either leading or lagging with respect to thepotentials impressed upon the corresponding main anodes or groups.

My invention will be better understood from the following descriptionwhen considered in connection with the accompanying drawings and itsscope will he claims.

Referring to the drawings, Fig. l is a diagrammatic representation of avapor electric apparatus, including a mercury arc device, in which myinvention has been embodied; Fig. 2 is a cross sectional view of themercury arc device included in Fig. 1, this view illustrating themounting of pointed out in the appended elements, as cathode, mainanodes, excitation.

anodes and baflie elements, included in this device; and Figs. 3 to 8are diagrammatic representations of vapor electric apparatus embody ingmodifications of my invention.

i In Fig. 1 my invention is illustrated as emadapted to fire or. pick upthe arc in sequence in the order indicated by the numerals denominatingthese anodes, the rotation of the firing or are pick-upbeing assumed tobe clockwise in the example shown in Fig. 1. To form the cathode spot onthe surface of the mercury cathode l4, a usual ignition anode apparatusincluding an ignition anode 21, operating solenoid 28 and spring 29 maybe provided.

As illustrated in Fig. 2, the main anodes, only i one. of which is shownin this figure denominated by the numeral 30, may be enclosed within ananode shield 3| extending downwardly within the evacuated receptacle 32and having a baflie 33 and a grid 34 mounted in the arc path within theshield, the members 32, 33 and 34 all functioning in part at least asbaflle elements in the arc paths between the main anodes, as 30,

. and the cathode l4.

In the embodiment of my invention illustrated diagrammatically in Fig. 1and in certain details in Fig. 2 the excitation means in accordent groupof two each of the -main anodes l5 2i, each of the excitation anodes 354. being mounted between-the two main anodes constituting thecorresponding group thereof. As will be evident from an inspection ofFig. 1 and of the cross sectional view of Fig. 2, the excitation anodes,only one of which is shown in Fig. 2 denominated by the numeral 4|, aremounted in the regions of the main anodes, each excitation anode beingclosely'adjacent the anode shield members of the corresponding pair ofmain anodes and relatively high up in the evacuated receptacle 32, forexample preferably at least as high above the cathode as the. mainanodes;

To energize the excitation anodes 35 40 each of the latter is preferablyconnected through The connections of auxiliary transformer 43 areassumed'to be so arranged that the six excitation anodes 35 i 40 fire orcarry current in sequence in the order indicated by the numeralsdenominating these anodes, the rotation of the firing, therefore, beingclockwise as in the case of the firing of the main anodes i5 26.Further, the connections of main transformer I3 and auxiliarytransformer 49 are assumed to be such that the positive half-waves ofthe potentials impressed upon each of the excitation anodes, firingin'the sequence 35' 4li, occur during the positive half-waves of thepotentials impressed upon the corresponding groups of main anodes,firing in the sequence l5, l6 25, 26.

The current-carrying periods of the excitation anodes 35 4. may besubstantially synchronized with those of the corresponding groups I 5,l6 25, 26 of the main anodes. Preferably, however, a suitablephase-shifting means,

such as a phase shifter connected between the auxiliary transformer 43and alternating current circuit Il, may be provided to cause .the phaseof the potentials impressed upon the excitation anodes 35 40 to beshifted either leading or lagging with respect to the potentialsimpressed upon the corresponding groups i5, i6 of the main anodes;

The operation of my invention will be clearly understood from thedrawings and from the foregoing description of one embodiment thereof.In operation, potentials from main transformer "and auxiliarytransformer 49 are impressed upon the mainanodes l5 26 and theexcitation anodes 3i 44 respectively, and at the same time the cathodespot is formed upon the cathode 14 by operation of the ignitionapparatus 21, 2|, 2! in the usual manner.

The potentials from transformer l3, existing upon the main anodes l5 26at the same time that the cathode spot is formed, tend to cause theseanodes to fire, or pick up the arc in sequence. IIeretofore a certaindegree of ion--- ization tending to assist in the pick-ur of the are bythe main anodes has been supplied to these anodes from excitation" orholding anodes the principal purpose of which was to maintain an arc inthe device at low loads when the arc at the main anodes tended to fall.But in many instances the pick-up of the are, thus incidentally assistedby the action of holding anodes designed primarily for another purpose,has been difllcult or even impossible, due, for example in the largepower high voltage mercury arc devices hereinbefore mentioned, to thepresence of baflle elements, such as the anode shields 3|, the battlemembers 33 and the grids 34, associated with the main anodes or in thearc path between these anodes and the cathode H. n

In the operation of the excitation means in accordance with my inventionthe pick-up of the are by the main anodes l5 26 is, however, made easyand certain by the action' of the excitation anodes 40 each associatedin the l5, It to 25, 28 in close juxtaposition to these anodes. 3

To make certain'that just suflicient ionization is supplied to eachgroup of mainanodes to overcome hard pick-up or the are without causingarc-back due to too great a degree of ionization in the receptacle l2,in accordance with my invention the potentials supplied ,by auxiliarytransformer 49 are impressed upon the excitation anodes 35 III in thesame sequence as that of the potentials impressed by main transformer l3upon the groups of main anodes l5, l6 25, 26 and in such .a manner thatthe ionization supplied to each group from its corresponding excitationanode occurs either sub-v stantiallysynchronously with the firing periodof the group, or lagging or leading this firing period-by a number ofdegrees determined by the phase shifting means. Preferably, in usualcases the phase of the potentials impressed upon the.

excitation anodes should beslightly leading with respect to the firingperiods of the main anode groups in order that ionization 'maybepresent, in any given group region, immediately preceding the firingperiod of the group.

My invention has been described and illustrated in connection withavapor electric device including one excitation anode for a group of mainanodes, the groups in the present example being constituted each by twomain anodes. It will be clearly understood, however, that the startingarrangement in accordance with my invention may include other numbersofexcitation anodes relative to the number of main anodes. For example,the number of excitation anodes may be the sameas that of the mainanodes as illustrated in Fig. 3, wherein the numerals 5| and 52designate the main and excitation anodes respectively. Or the number ofexcitation anodes may be the same as the number of groups of mainanodes, the constituent main anodes of the-groups being arranged,however, for parallel operation, as illustrated in Fig. 4, wherein thenumerals 54 and 54' designate pairs of main anodes arranged for paralleloperation and the numerals 55 designate the excitation anodes. Further,each excitation anode may be associated with a group constituted by morethan two main anodes as illustrated in Fig. 5. For example, in

. a vapor electric device provided with twenty-four main anodesdesignated by the numerals 58, six

excitation anodes designated by the numerals 51, or one for each groupof four main anodes may be suflicient.

It will be understood, further, that while the plurality of excitationanodes have been described as so disposed that each is in the sameposition with reference to the main anodes, the excitation anodes may bevariously arranged. For example, certain of the excitation anodes may beat one level within the evacuated container and others at a differentlevel as illustrated in Figs. 6 and 7 which are plan andcross-sectionalviews respectively of a' rectifier in which the invention is embodied.The numerals 58 designate the main anodes and numerals 59 and 60represent two sets of excitation anodes mounted at difierent levelswith'respect tothe mainanodes.

It will also be understood that in certain cases the set of excitationanodes furnishing the ionization for the main anodes are necessarilyplaced in such a position that these excitation anodes themselvesrequireto be assisted in starting, or

pickingup their excitation are from the cathode,

by ionization supplied to them from a second v set of excitation anodesmounted closer to the cathode. Thus in the modification shown in Fig. 8,wherein the numerals 6i designate the main anodes, one set of excitationanodes designated by the numerals 62 may be mounted as in the embodimentof. the invention shown in Fig.1 and a second set of excitation anodesdesignated by the numeral 62 may be mounted nearer the cathode. In thiscase, in igniting the set of excitation anodes associated directly withthe main anodes and which are necessary in order to obtain successfulstarting of these main anodes, the ionization must migrate from one setof excitation anodes to another set, or other sets in sequence, andfinally to the main anodes.

What I claim as new and desire to secure by Letters Patent in the UnitedStates is:

l. The combination with apolyphase vapor electric apparatus including aliquid cathode, means to form a cathode spot'thereon, a plurality ofmain anodes arranged to carry current in a predetermined sequence, and aplurality of anode shields having ba'flle members mounted therein, saidshields and baflle members being so arranged with reference to thecorresponding main anodes as to tend to prevent pick-up of the are bysaid main anodes, of a plurality of excitation anodes arranged to carrycurrent to said cathode spot inthe same sequence as that of the mainanodes, said excitation anodes being respectively adjacent to thecorresponding main anodes and arranged to supply ionization therefor tofacilitate picking up; of the are thereby.

2. The combination with a' polyphase vapor electric apparatus includinga liquid cathode, means to form a cathode spot thereon, a plurality ofgroups of main anodes arranged to carry current in a predeterminedsequence, and a plurality of anode shields. having baiiie membersmounted therein, said shields and baffle members tending to preventpick-up of the are by said main anodes, of a plurality of excitationanodes main anodes, each of said excitation anodes being.

mounted adjacent a diflerent one of said groups to supply ionization tothe main anodes constituting the corresponding one of said groups tofacilitate picking up of, the are thereby.

' apparatus including a liquid cathode, means to 3. In combination, apolyphase vapor electric apparatus'including a liquid cathode, means toform a cathode spot thereon, a plurality of main anodes, and a pluralityof anode shields having baiile members mounted therein, said shields andbaiile members tending to prevent pick-up of the are by said mainanodes, means to impress potentials upon said main anodes in sequence, aplurality of excitation anodes mounted respectively adjacent tothecorresponding main an odes, and means to impress in sequence uponsaid excitation anodes potentials suflicient to cause discharge currentto flow between said excitation anodes and said cathode spot, saidpotentials being substantially synchronized with the corresponding mainanode potentials whereby ionization is supplied to the main anodes insequence from the corresponding excitation anodes for facilitating thepicking up of thearc by saidmain anodes. v V

4. In combination, a polyphase vapor electric form a cathode spot onsaid cathode, a plurality of main anodes, and a plurality of anodeshields having bailie members mounted therein, said shields and baillemembers tending to prevent pick-up of the are by said main anodes, meansto impress potentials upon said main anodes in sequence, a. plurality ofexcitation anodes mount-:-

ed respectively adjacent to the corresponding main anodes, means toimpress upon the excitation anodes potentials suflicientto initiatecurrent flow from said excitation anods to said cathode spot and in asequence corresponding to that of the potentials impressed upon themain' anodes, whereby ionization is supplied to 'the main anodes insequence from the corresponding. excitation anodes for facilitating thepicking up oi the are by the main anodes, and means to determine thephase of the excitation anode potentials with relation to the phase ofthe corresponding main anode potentials.-

5. In combination, a polyphase vapor electric apparatus including amercury cathode, means to form a cathode spot on said; cathode and aplurality of main anodes, means to impres in-sequence upon said mainanodes potentials tending to cause pick-up oi the are between cathodeand anodes, means in said apparatus tending to prevent said pick-upcomprising a plurality oi. anode shields having baifle members mountedtherein, a plurality of excitation anodes adjacent respectively to thecorresponding main anodes, and

means to impress potentials upon said excitation anodes sufficient toinitiate current flow from said excitation anodes to said cathode spotwhereby ionization is supplied to each of said main potentials tendingto cause pick-up of the are between cathode and anodes, means in saidapparatus tending to prevent saidpick-ilpa plurality of excitationanodes each associated with a difierent one oi! said groups of mainanodes, and

means to'impress potentials upon said excitation anodes to supplyionization to each of said groups, said ionization being of such amountand each of said excitation anodes being so disposed with'reterence tothe region in said apparatus of the corresponding group of main anodesthat the tendency of said second-named means to prevent said pick-up isovercome without said ionization being sufllcient to cause arc back insaid apparatus.

7. In a polyphase vapor electric apparatus including a mercury cathode,means to forma cathode spot on said cathode, a plurality of main anodesand means to impress thereon alternating potentials to cause said mainanodes to pick up members mounted therein, said shields and bafllemembers tending to prevent said pick-up, and a plurality of excitationanodes, the method of facilitating the pick-up of the are by the main 1anodes which includes impressing upon the excitation anodes alternatingpotentials suilicient to initiate discharges between said excitationanodes and said cathode spot and in thesame sequence as that of thecorresponding main anode potentials, and supplying ionization from eachof the excitation anodes to at least one of the corresponding mainanodes.

8. In a polyphase vapor electric apparatus including a mercury cathode,means to form a cathode spot on said cathode, a plurality of main anodesand'means to impress upon said anodes in sequence alternating potentialstending to cause said main anodes to pick up the arc in said apparatus,means in said apparatus tending to prevent said pick-up of the arc,comprising a plurality of anode shields having bailie members mountedtherein and aplurality of excitation anodes adjacent respectively to thecorresponding main anodes, the method of operation which includesimpressing potentials upon the excitation anodes sufilcient toinitiatedischarges between said excitation anodes and said cathode spot,thereby to supply to' each oi the main anodes sufilcient ionization toovercome the tendency of said last-named means to prevent pick-up of theare by the main anodes,- said ionization being at the same timeinsufii'cient to cause are back in the apparatus.

9. In a polyphase vapor electric apparatus including a mercury cathode,means to form a cathode spot on said cathode, a plurality of main anodesand means to impress upon said anodes in sequence alternating potentialstending to cause said main anodes to pick up the arc in said apparatus,means in said apparatus tending to prevent said pick-up of the arc, aplurality of anode shields having baiile members mounted therein, saidshields and baflle members tending to prevent said pick-up, and aplurality oi excitation anodes adjacent respectively to thecorresponding main anodes, the method of operation which includesinitiating discharges between said excitation anodes and said cathodespot to supply from the excitation anodes to the main anodes ionizationin such amount and so disposed with reference to the regions 01' themain anodes that said tendency of the said secondnamed means to preventpick-up of the are by the main'anodes is overcome, said ionization beinginsumcient to cause are back in the apparatus.

10. In a vapor electric apparatus including a mercury cathode, means toform a cathode spot on said cathode, a plurality of main anodes,

to pick up the arc in said apparatus in a predetermined sequence, and aplurality of excitation anodes, the method of operation which includesimpressing upon the V excitation anodes alternating potentialssufficient to initiate discharges between said excitation anodes andsaid cathode spot, said excitation anode potentials being in the samesequence as that of the corresponding main anode potentials, anddetermining the phase of the excitation anode potentials with relationto the corresponding main anode potentials.

11. In a polyphase vapor electric apparatus in cluding a mercurycathode, means to form a cathode spot on said cathode, a plurality ofmain anodes, means to impress thereon alternating potentials to causesaid main anodes to fire in a predetermined sequence, a plurality ofanode, shields having baflle members mounted therein, said shields andbaiiie members tending to prevent said pick-up, and a plurality ofexcitation anodes, the methodof operation which includes impressinguponthe excitation anodes alternate rality oi anode shields having banemembers mounted therein, said shields and baille members tending toprevent pick-up of the are by said main anodes, of a plurality ofexcitation anodes arranged to carry current in the same sequence as thatof the main anodes, said excitation an-. odes being respectivelyadjacent to the corresponding main anodes and arranged to supplyionization therefor to facilitate picking up of the arc thereby, certainof said excitation anodes being mounted in said receptacle at one levelwith respect to said main anodes and others of said excitation anodesbeing mounted at a dif- Ierent level with respect to said main anodes.

'13. The combination, with a polyphase vapor electric apparatus,including a. mercury cathode, a-pliirality oi. main anodes arranged tocarry current in a predetermined sequence, and, a plurality of anodeshields having baflie members mounted therein, said shields andbaille'members tending to prevent pick up of the are by said mainanodes, of a plurality of excitation anodes respectively adjacent to thecorresponding main Y anodes and arranged 'to carry current in the samesequence as that of the main anodes, and a second plurality ofexcitation anodes mounted closer than said first-named excitation anodesto said cathode, said second plurality, of excitation anodesbeingarranged to supply ionization to/said first-named plurality ofexcitation anodes to facilitate picking up of the are by said firstnamedexcitation anodes, said first-named excitation anodes being arranged tosupply ionization to said main anodes to facilitate I V picking up ofthe are by said main anodes.

I LYSLE W. MORTON.

CERTIFICATE or cossscrron.

Patent No. 2,059,014.}

October z'r,. 19ss.

LYSLE wQtonrou,

.I t is hereby certified that error appears in the printed specificationor the above numbered patent requiring correction 'asfollows: I Page 4,strike out all of cla m 6; same page, second column, line -71, claim 10,before the i word "vapor" insert polyphase; page 5, first column, line1., same claim, after the comma and before "and" insert the words andcomma a. plurality of anode shields having baffle members mountedtherein, said shields and baffle members tending to prevent 'saidpick-up,

-'lhe claims now appearing inthe patent as 7, 8, 9, 10, ll, '12 and 18should bear the numbers 6, 7, 8, 9, 10, '11 and 12 respectively; andthat the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Office.

- Signed and sealed this 12th day of January a. D. 1937.

(S eal) l 1 m vaniirmio Acting Commissioner of Patents.

said apparatus in a predetermined sequence, and a plurality ofexcitation anodes, the method of operation which includes impressingupon the V excitation anodes alternating potentials sufficient toinitiate discharges between said excitation anodes and said cathodespot, said excitation anode potentials being in the same sequence asthat of the corresponding main anode potentials, and determining thephase of the excitation anode potentials with relation to thecorresponding main anode potentials.

11. In a polyphase vapor electric apparatus in cluding a mercurycathode, means to form a cathode spot on said cathode, a plurality ofmain anodes, means to impress thereon alternating potentials to causesaid main anodes to fire in a predetermined sequence, a plurality ofanode, shields having baflle members mounted therein, said shields andbaiiie members tending to prevent said pick-up, and a plurality ofexcitation anodes, the methodof operation which includes impressinguponthe excitation anodes alternate rality oi anode shields having banemembers mounted therein, said shields and baille members tending toprevent pick-up of the are by said main anodes, of a plurality ofexcitation anodes arranged to carry current in the same sequence as thatof the main anodes, said excitation an-. odes being respectivelyadjacent to the corresponding main anodes and arranged to supplyionization therefor to facilitate picking up of the arc thereby, certainof said excitation anodes being mounted in said receptacle at one levelwith respect to said main anodes and others of said excitation anodesbeing mounted at a dif- Ierent level with respect to said main anodes.

'13. The combination, with a polyphase vapor electric apparatus,including a. mercury cathode, a-pliirality oi. main anodes arranged tocarry current in a predetermined sequence, and, a plurality of anodeshields having baflie members mounted therein, said shields andbaille'members tending to prevent pick up of the are by said mainanodes, of a plurality of excitation anodes respectively adjacent to thecorresponding main Y anodes and arranged 'to carry current in the samesequence as that of the main anodes, and a second plurality ofexcitation anodes mounted closer than said first-named excitation anodesto said cathode, said second plurality, of excitation anodesbeingarranged to supply ionization to/said first-named plurality ofexcitation anodes to facilitate picking up of the are by said firstnamedexcitation anodes, said first-named excitation anodes being arranged tosupply ionization to said main anodes to facilitate I V picking up ofthe are by said main anodes.

I LYSLE W. MORTON.

CERTIFICATE or cossscrron.

Patent No. 2,059,014.}

October z'r,. 19ss.

LYSLE wQtonrou,

.I t is hereby certified that error appears in the printed specificationor the above numbered patent requiring correction 'asfollows: I Page 4,strike out all of cla m 6; same page, second column, line -71, claim 10,before the i word "vapor" insert polyphase; page 5, first column, line1., same claim, after the comma and before "and" insert the words andcomma a. plurality of anode shields having baffle members mountedtherein, said shields and baffle members tending to prevent 'saidpick-up,

-'lhe claims now appearing inthe patent as 7, 8, 9, 10, ll, '12 and 18should bear the numbers 6, 7, 8, 9, 10, '11 and 12 respectively; andthat the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Office.

- Signed and sealed this 12th day of January a. D. 1937.

(S eal) l 1 m vaniirmio Acting Commissioner of Patents.

